1. Field of the Invention
The present invention relates to a slide member adapted to perform linear motion along a shaft, and is suitable for a slide member which is installed in the information equipment, for example, in the carriage of a printer.
2. Description of Prior Art
The carriage instilled in a printer performs linear motion as guided by one or more shafts, and to guide this carriage in linear motion, the carriage is provided with a bearing (slide member) which slides on the outer peripheral surface of said shaft. Conventional slide member of this type is generally made of resin (100% resin) or an oil-impregnated sintered alloy (100% metal).
In recent years, there has been a trend toward a strong desire for calmness during printer operation, and correspondingly thereto, further noise reduction is required of the slide member which is one source of noise. Further, in a slide member made of resin, since it is formed by injection molding or machining such as cutting, problems pointed out are that high dimensional accuracy can hardly be attained and that the cost is high.
Accordingly, an object of the invention is to provide a slide member having such features as low noise, producibility with good accuracy, and low costs.
To achieve the above object, according to the invention, the slide member slidably guided on the outer peripheral surface of a shaft is made by adding thermosetting resin to a metal powder consisting mainly of copper powder, iron powder or a mixture thereof, and sintering the same.
As the slide member is made by adding thermosetting resin to a metal powder, and sintering the same, as described, the presence of the resin improves the damping property, eliminating the echoing of sound and the accentuation of sliding sound as is the case with the conventional sintered oil-impregnated bearing (100% metal), thus making it possible to suppress the sliding sound produced during linear motion so as to secure a high degree of calmness. Further, being a sintered body allows shaping to a predetermined size as by press-forming after sintering, thus achieving increased accuracy and reduced costs as compared with the resin bearing which requires machining or injection molding.
Said mixture of a metal powder and resin is desirably sintered at temperatures not less than the carbonization temperature of the resin, whereby a slide member which is high in hardness and in strength is obtained.
Use of a thermosetting resin which is of the hot-melt type, that is, having the property to set after it is melted by heating (hot-melt self-setting property) provides increased strength.
Adding tin or copper to said metal powder and subjecting the same to the liquid phase sintering results in increased strength being obtained since the additive metal serves as a binder.
The thermosetting resin is added preferably in an amount of 10-50% by volume. The porosity of the slide member is set preferably to 5-40% by volume. This range ensures that lubricating oil necessary for lubrication can be held stably in a long time, prolonging the life of the slide member.
The compacted body of said mixture is shaped after sintering This process is economical as it needs no cutting operations and yet high dimensional accuracy is attained.
The slide member should have an axial groove in the inner diameter region This groove functions as an oil sump, ensuring that ample oil is held between the shaft and the slide member, improving lubricity.
A carriage having the slide member described above has a high degree of calmness and is guided with high accuracy, so that the operational stability is high, and yet the cost is low.